On the one hand, this invention relates to a method for weaving a fabric, characterized in that in successive work cycles of a weaving machine a shed is formed between the warp threads of a number of warp thread systems and one weft thread is inserted in this shed at a weft insertion level, and characterized in that, in each shed, the warp threads are positioned in relation to the weft insertion level in a manner that, together with the inserted weft threads, they form a fabric that displays on both sides figure shaping warp threads and on the other hand, this invention relates to a weaving machine to apply this method according to the invention.
The invention furthermore relates to a weaving machine provided to realize such method as well as to a fabric that on both sides displays figure shaping warp threads.
Fabrics with two useable sides are formed, on the one hand, from weft threads that are inserted crosswise in the fabric and, on the other hand, from warp threads that are fed lengthwise for fabric structuring, on the one hand comprising figure warp threads that are positioned in relation to the weft threads, in order to shape the desired figure, and, on the other hand comprising binding warp threads that are inserted to bind over the weft threads and to define a fabric (structure).
In this patent application, the term ‘figure warp threads’ means: warp threads provided to enable working in a figure shaping way.
Optionally, also tensioning warp threads can be applied, in order to position the weft threads also in the height direction in relation to each other and to realize new aspects and higher densities. During the weaving process, the warp threads are always positioned in relation to the one or more weft insertion levels, called shed formation, in order to subsequently insert the one or several weft threads and to press the weft threads by means of the reed against the fabric edge with the purpose of adding a fabric line to the fabric in this manner. Upon this, the warp threads take up a new position in relation to the weft insertion means, which corresponds with the desired binding structure and the desired figure shape, the one or several weft threads are again inserted and the reed presses the inserted weft threads against the fabric edge. This cycle is continually repeated until the desired fabric is formed.
Fabrics with two useable sides with figure shaping on both sides of the fabric are already known. First, there is the well-known Kelim weaving technique in which, over a system of adjacently running warp threads, through an up and down movement, over a certain section of the width, weft threads are woven between the warp threads (according to the desired figure), in order to be re-conducted at the end of said section of the width and to be woven at the other side of the fabric and in the same manner in the returning direction between the warp threads in such manner that the weft threads cover the warp threads. The different weft threads, positioned adjacently to each other in the weft direction, are woven together so that no “tear” is created for any vertical lines in the drawing. The result is a fabric with two useable sides with the same figure on both sides. The fabric is produced manually because the wefts are to be inserted only over a limited section of the width.
Additionally, in plain weaving, there are known techniques such as, for instance, Gobelin weaving with double-sided weft as described in: Die Weberei by Ernst Gräbner, published in 1951 by Fachbuchverlag GmbH—Leipzig (pp 304 to 311). In this document is described how by insertion of multiple wefts with different properties (color, structure) a fabric with two useable sides can be woven with a different (or same) figure pattern on both sides. This can be done by means of two figure shaping weft threads, with different properties, which are inserted one after the other. By insertion of a “stem warp yarn”, which each time is positioned between both weft threads, it is determined which weft thread will become figure shaping at which side of the fabric with two useable sides. A weft thread that in a certain place in the fabric is used at the topside can no longer be used at the same place at the bottom side and vice versa. By this, a complementary fabric is created, namely a fabric in which different weft threads shape one and the same figure both at one side and at the other side of the fabric, with the characteristic that weft thread 1 determines the effect (color, structure) at one side, whereas weft thread 2 does this at the other side.
These effects alternate simultaneously from one side to the other in order to shape a figure in this way, which, at both sides, only differs from the other one by the effect realized by both yarn types.
By inserting more figure shaping weft threads, different figures can be shaped at the topside and the bottom side of a fabric with two useable sides, on condition that a second “stem warp yarn” is added to separate the non-figure-shaping weft threads from the weft threads shaping figures at both sides of the fabric. The disadvantage of this method is, on the one hand, that per woven fabric line (realized per beat of the reed) at least as many weft threads as there are figure shaping weft threads active in that fabric line must be inserted and, on the other hand, that two “stem warps” are required when inserting more than two figure shaping weft threads. Moreover, it is a well-known fact that figure shaping weft threads are not always very suitable to be inserted as weft threads. This is in particular the case for weaving machines with air jet insertion, given that not all figure shaping yarn kinds are suitable to be inserted as weft yarn through a shed by means of a jet of air. In warp direction, this limitation does not apply.
As, by this technique, at the figure shaping side, only one weft lies above the stem warp yarn, said technique does not allow weaving of rib-shaping fabrics by positioning multiple wefts above one another, as, in a case like this, we cannot say with certainty which one of both wefts will be figure shaping. In addition, it is a fact that effect yarns in weft direction cannot be fixed as firmly between the warp threads as effect yarns in warp direction can be fitted between the weft threads. In weft direction, they are inserted in one cycle over the entire width; in warp direction, cycle per cycle, they are pressed against the fabric edge under warp tension by the beating movement of the reed.
European patent publication EP 0 974 689 describes how a double-sided fabric is produced with figure shaping warp threads, characterized in that, per warp yarn, an additional warp thread is inserted and two weft threads are superposed. The additional warp keeps both weft threads further apart from each other and, as such, provides a more pronounced rib effect to both sides of the fabric. A disadvantage of such method is increased yarn consumption, on the one hand, due to the requirement for an additional warp thread that will be nowhere visible and, on the other hand, because of the necessity to insert two weft threads per figure shaping loop.
In FIG. 2 of European patent publication EP 0 974 690, a method is shown and described in which two rib-shaping fabrics are woven according to the double face principle, characterized in that the non-active pile warp threads are not bound in along the tensioning warp thread but are woven in a wavy manner and alternately over a weft thread located at the topside of the fabric in relation to the tensioning warp thread and over a weft thread located at the bottom side of the fabric in relation to the tensioning warp thread. The thus formed fabric is ribbed at one side by loops supported by a weft thread, so-called false loops. Moreover, the herein-described fabric has an additional weft thread to form the false loop. The hereby-created fabric with two useable sides, with figure shaping at both sides, has the disadvantage of comprising two sides with dissimilar properties because of the one-sided rib formation.
In double-sided fabrics with figure shaping threads, we are confronted with the problem that we have to position the threads that are capable of figure shaping in such relation to each other that, at the bottom and at the top of the fabric, the desired figure shaping threads will become visible and the others will remain invisible. With the prior art, we work on the one hand with figure shaping weft threads that are kept apart from each other by one or more “stem warps”. This has as disadvantage that a fabric line can only be added to the fabric after insertion of a number of wefts by an amount that is at least equal to the number of figure shaping weft threads inserted in the fabric line. In other words, several weft threads are needed for each fabric line added to the fabric. Moreover, additional warp threads are needed, which ensure that the adjacently inserted weft threads place themselves in the desired sequence above one another. Weft threads inserted in this manner can never be woven as firmly between the warp threads as figure shaping warp threads can be woven between the weft threads.
On the other hand, we work with warp threads as figure shaping yarns and, until today, in relation to each weft insertion level, we only worked with two positions to position the weft threads: above the weft insertion device or below the weft insertion device. When, during the shed formation, we simultaneously move two figure shaping warp threads in this manner from one same position to another same position (from a position above the weft insertion device to a position below the weft insertion device or vice versa), we cannot predict which warp thread will fix itself against the weft thread and which weft thread will fix itself to the outer side of the fabric and will be figure shaping. In the prior art, this was solved by, for instance, working with two weft threads above one another and by providing an extra warp thread between the two weft threads.
The purpose of the invention is to provide a method and a system by which a fabric, displaying figure shaping warp threads at both sides, can be produced without the mentioned disadvantages.
In this patent application, the term ‘figure shaping warp threads’ is used in the sense of figure warp threads that are effectively shaping a figure. ‘Non-figure-shaping warp threads’ are figure warp threads that, at some location in the fabric, are not figure shaping.
This purpose is met by providing a method for weaving a fabric with the properties as indicated in the first paragraph of this description, characterized in that at least one warp thread system comprises a first and second figure warp thread that, in a number of operating cycles, are positioned together alternately above and under the weft insertion level, so that, at both fabric sides, these figure warp threads are bound over the same weft threads, while running above one another, the upper figure warp thread being figure shaping at the topside of the fabric and the lower figure warp thread being figure shaping at the bottom side of the fabric, and characterized in that, according to this invention, during the weaving process, the mutual position taken up in the fabric by the first and the second figure warp thread is determined selectively according to a previously defined figure pattern.
In this way, the purpose of the invention is realized. On a weaving machine, a fabric with two useable sides is manufactured with figure shaping at both sides, by means of warp threads, according to a method by which only one weft thread per operating cycle of the weaving machine is to be inserted and in which no additional warp threads are required.
In such method, in order to realize the desired binding structure for the weft threads, also ground warp threads can be positioned in the successive sheds.
In the method according to the invention, the cited first and second figure warp threads are preferably positioned in a first shed at a first level at one side of the weft insertion level and in a second shed at a different second level and third level at the other side of the weft insertion level, while the positions of the first figure warp thread and the second figure warp thread in the second shed determine the aforementioned mutual position of both figure warp threads running above one another, said positions being determined during the weaving process according to a previously defined figure pattern.
More in particular, in the second shed, the positions of the first warp thread and of the second figure warp thread determine said the mentioned mutual position of the above one another running figure warp threads, when they are bound over the weft thread inserted during the first shed.
In a very preferred method according to this invention, the figure warp thread that is positioned in the second shed in the position located nearest to the weft insertion level, takes up the figure shaping position in the fabric when bound over the weft thread that was inserted during the first shed.
In a particular implementation of the method according to the invention, alternately a first and a second shed are applied.
The method according to this invention runs more efficiently when the first and the second figure warp thread on the weaving machine are not separated from each other by a weaving machine element, such as a reed dent or a spacer. Preferably, the first figure warp thread and the second figure warp thread are provided adjacent to each other on the weaving machine.
In another particular implementation of the method according to the invention, per warp thread system, at least one tensioning warp thread is provided and the successive weft threads are provided alternately above and below the tensioning warp threads, so that a fabric with two layers of weft threads is shaped. By providing tensioning warp threads, the successive wefts are positioned in layers above and below these tensioning warp thread, which allows hiding of any additional figure warp threads between these successive wefts without need for extra stem warp threads as is the case in the method with figure shaping weft threads.
In an especially advantageous implementation of the method according to the invention, the first and/or the second figure warp thread remain positioned above or below the weft insertion level for several operating cycles. This allows introducing yet more variation into the figure shape.
In a preferred method according to the invention, at least one warp thread system comprises a group of at least three figure warp threads of a different color or aspect, while the two figure warp threads that, during a number of operating cycles, together are bound into the fabric in a figure shaping manner are selected from this group according to the desired figure pattern at both fabric sides, whereas every other figure warp thread of the group is bound into the fabric in a non-figure-shaping manner during these operating cycles. Such method allows adding additional colors and structures into the fabric.
Preferably, each in non-figure-shaping figure warp thread is bound in the fabric in a stretched manner and running together with a tensioning warp thread.
Addition of a third figure warp thread per warp thread system allows realizing fabrics with two useable sides that allow deviation from the complementary character of the figure pattern at both sides of the fabric. Indeed, with three figure warp threads it is possible to insert either at one side or at the other side an additional (not complementary) figure element at any location in the fabric. This is especially interesting when, for instance, we want to integrate text or logos in the fabric, as such text or logos are to form a different figure at both sides of the fabric in order to be readable. In such case, the text or logo cannot overlap with any text or logos at the other side of the fabric.
The latter is indeed possible in a special method according to this invention in which at least one warp thread system comprises a group of figure warp threads with a first pair of figure warp threads of a first color, structure or aspect and a second pair of figure warp threads of a second color, structure or aspect, and in which the two figure warp threads that, together, are bound into the fabric in a figure shaping manner always belong to the same pair. By this method, we can weave fabrics with two useable sides that are identical on both sides, so that, in this manner, fabrics can be woven that are very resembling to Kelim fabrics.
In another particularly preferred method according to the invention, all figure warp threads of a number of warp thread systems are bound in the fabric in a non-figure-shaping way for a number of operating cycles, so that, at least at one fabric side, at a certain location, the weft threads are visibly bound according to a previously defined figure pattern. By application of this method, yet other additional effects can be realized when shaping the figure. These effects can be realized by one same yarn type for the weft threads, but they can also be realized by inserting different yarn types for the weft threads, for instance, by means of a known weft selector.
A particular method provides that first and second weft threads of a different color or aspect can be inserted in a manner that the weft threads visible at a certain location comprise first as well as second weft threads.
In yet another method according to this invention, per warp thread system, at least one tensioning warp thread is provided and each tensioning warp thread is so positioned in relation to the weft insertion level that, at least at one fabric side, at a certain location, a number of weft threads are visibly bound according to a previously defined figure pattern. This allows additional effects during figure shaping.
Preferably, at least one tensioning warp thread is positioned by means of a jacquard arrangement.
The invention further relates to a method for simultaneous weaving of at least two fabrics on a weaving machine in which, per fabric, a described method according to this invention is applied virtually simultaneously to both fabrics.
The invention also relates to a method for simultaneous weaving of at least two fabrics on a weaving machine having at least a same number of weft insertion devices as there are fabrics to be woven, which are provided to insert weft threads at a respective weft insertion level, while, for each fabric, in successive operating cycles of the weaving machine, in relation to a different weft insertion level, a shed is formed between a number of warp threads of a number of warp thread systems in relation to a different weft insertion level and one weft thread is inserted in each shed, characterized in that, in each shed, the warp threads are positioned in relation to the related weft insertion level in a way that, together with the inserted weft threads, they form a fabric that displays figure shaping warp threads at both sides, and in which, per fabric, at least one warp thread system comprises a first figure warp thread and a second figure warp thread, which, together, are positioned in a number of operating cycles alternately above and below the weft insertion level, so that, at both fabric sides, these warp threads are bound over the same weft threads while running above one another, the upper warp thread being figure shaping at the topside of the fabric and the lower warp thread being figure shaping at the bottom side of the fabric, and in which, in each fabric, the mutual position taken up by the first warp thread and the second warp thread is selectively determined during the weaving process according to a previously defined figure pattern.
By this method, it is possible to produce simultaneously two fabrics with two useable sides. Such weaving machine is preferably a face-to-face weaving machine.
In a particular method for simultaneous weaving of at least two fabrics on a weaving machine according to the invention, for each fabric, a method is applied, in which the mentioned first and second figure warp threads are positioned in a first shed at a first level at one side of the weft insertion level and in a second shed at a different second and a third level at the other side of the weft insertion level, while the positions of the first and the second figure warp thread determine the mentioned mutual position of the two figure warp threads running above one another in the second shed, said positions being determined during the weaving process according to a previously defined figure pattern, and, in relation to two weft insertion levels located above one another, upon positioning of first and second warp threads in the mentioned first and second sheds, the lower level is provided in relation to the upper weft insertion level above the lower weft insertion level.
The lower level in relation to the upper weft insertion level is preferably located above the upper level in relation to the lower weft insertion level. Such system presents the advantage that the warp threads have to cross less often.
In a particularly preferred method for simultaneous weaving of at least two fabrics on a weaving machine according to the invention, the first and second warp threads are located at both the mentioned first level in relation to the upper weft insertion level and the mentioned first level in relation to the lower weft insertion level between the weft insertion devices operating at these weft insertion levels.
In another particularly preferred method for simultaneous weaving of at least two fabrics on a weaving machine, the first and second warp threads are located at both the mentioned second and third levels in relation to the upper weft insertion level and the mentioned second and third levels in relation to the lower weft insertion level between the weft insertion devices operating at these weft insertion levels.
In a particularly advantageous method for simultaneous weaving of at least two fabrics on a weaving machine, in at least one warp thread system at least one figure warp thread is positioned in a way that it is bound alternately over a weft thread of an upper fabric and over a weft thread of a lower fabric, and cut between these fabrics so that on the facing fabric sides respective areas with cut pile are formed. This is particularly interesting because, in this manner, the special additional effect of cut pile is added to one of the fabric sides.
Such fabrics can be used at both sides, for instance, when they are hung up to divide a space in two separate spaces. The mentioned cut pile effect is then visible at on side of the suspended fabric.
Another object of this patent application is a weaving machine comprising shed formation devices provided to form a shed in successive operating cycles between a number of warp threads, and a weft insertion device provided to insert during each operating cycle one weft thread at a weft insertion level in this shed, the shed formation devices being provided to bring two figure warp threads of a same warp thread system in a first operating cycle at a first level at one side of the weft insertion level and to bring these figure warp threads to a different second and third level at the other side of the weft insertion level in a second operating cycle.
With a weaving machine of this kind, we can produce a fabric according to this invention in a particularly efficient manner.
In a preferred embodiment, the weaving machine comprises at least two weft insertion devices provided to insert in each operating cycle one weft thread at a respective weft insertion level, as well as shed formation devices provided to form a shed in successive operating cycles in relation to each weft insertion level, characterized in that, in relation to each weft insertion level, the shed formation devices are provided to bring two figure warp threads of a same warp thread system to a first level at one side of the weft insertion level in a first operating cycle, and to bring both these figure warp threads in a second operating cycle to a different second and third level at the other side of the weft insertion level. Said second and third levels are preferably situated between two weft insertion levels located above one another.
In a more preferred embodiment of a weaving machine according to the invention, said weaving machine is provided to perform alternately a first and a second operating cycle.
In a particular embodiment of a weaving machine according to the invention, the distance between the mentioned second and third level is smaller than the distance between the first level and the second level. As, for performing of the method according to this invention, no weft insertion device must be passed between these two positions that are located along the same side of the weft insertion level (the mentioned second and third level), these positions can be closer to each other that the positions located at either side of the weft insertion level (first and second level).
This can be realized by a jacquard arrangement with more than three positions, of which one position coincides with the weft insertion level and in which this position is not being used. If, in this weaving machine, a distance L is provided between the positions that at both sides are located closest to the weft insertion level (first and second level), then the distance between the two positions located at the same side of the weft insertion level (second and third level) equals L/2.
This can also be realized by a suitable pulley system, possibly in combination with a grid moving in phase or in counter phase together with the driving blades.
In a preferred weaving machine according to this invention the distance between the mentioned second and third level is preferably about one half of the distance between the first and the second level.
To realize this, the weaving machine according to the invention comprises in a preferred embodiment a jacquard arrangement to bring the warp threads to the first level, the second level and the third level. In a preferred embodiment, said jacquard arrangement is a non-open-shed jacquard arrangement, preferably a non-open-shed jacquard arrangement with at least three positions. In a most preferred embodiment, the jacquard arrangement is an open-shed jacquard arrangement, preferably with three or more positions, by which thus at each shot (at each insertion of a weft thread) each one of these three or more positions can be reached.